A158411 - OEIS

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A158411

Maximum number of colors required to paint a map having n regions.

0, 1, 2, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4

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OFFSET

0,3

COMMENTS

The generating function can be arranged to have four zeros at the fourth roots of unity. - Jaume Oliver Lafont, Mar 23 2009

Also, the arithmetic function uhat(n,4,3) as defined in A291041. - Robert Price, Aug 25 2017

Decimal expansion of 1111/90000. - Elmo R. Oliveira, May 06 2024

LINKS

Table of n, a(n) for n=0..100.

Eric Weisstein's World of Mathematics, Four-Color Theorem

Wikipedia, Four color theorem

Index entries for linear recurrences with constant coefficients, signature (1).